Ready-mix concrete using recycled concrete aggregate

ABSTRACT

A ready-mix concrete and method for making the ready-mix concrete having mix proportions that include at least 70% course recycled aggregate and fly ash is provided. The ready-mix concrete including cement, air, water, sand and a remaining percent of virgin course recycled aggregate such that the coarse recycled aggregate combines to 100% of the required course aggregate.

CLAIM OF PRIORITY UNDER 35 U.S.C. §§119 AND 120

The present application claims priority to the U.S. provisional patentapplication Ser. No. 60/971,800, titled READY-MIX CONCRETE USINGRECYCLED CONCRETE AGGREGATE, filed Sep. 12, 2007, the specification ofwhich is incorporated herein as if set out in full.

REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT

None.

BACKGROUND

1. Field

The technology of the present application relates to ready mix concrete,and more specifically to ready mix concrete using recycled concreteaggregates.

2. Background

Using concrete for construction of roads, buildings, tarmacs, and thelike has existed for centuries. Concrete provides a strong and formablebuilding material. Because it is strong and formable, use of concrete inconstruction of roads, building, tarmacs, and the list has existed forcenturies. While concrete can be formed of many materials, today'sconcrete typically includes a cement (most typically Portland cement inthe United States), an aggregate (typically gravel and sand), and wateradmixture. Additional chemicals may be added depending on variousfeatures, such as hydration time, plasticizers, pigments, bondingagents, and the like.

Concrete can be mixed on-site in many applications. However, more andmore frequently, project sites use what is typically known as “ready-mixconcrete.” A manufacturing facility combines the cement, aggregate, andwater admixture to the specifications of the job site and in accordancewith American Society for Testing Materials (“ASTM”) requirements, whichinclude international standards. The ASTM requirements definecomposition requirements for the concrete as well as strength and otherrequirements.

As one can appreciate, the ease and versatility of concrete has lead toan abundance of older structures. These structures are in various statesof decay and/or in need of repair. While it is possible to tear downthese structures and replace them with newer structures, the result isan abundance of concrete debris and rubble.

Thus, against this background, it would be desirable to develop aconcrete that reuses or recycles used concrete debris and rubble.

SUMMARY

Embodiments disclosed herein address the above stated needs by providinga method to make ready-mix concrete wherein at least 70% of the coarseaggregate is recycled. The method including the steps of loading rawmaterial bins with material in mix proportions for a ready-mix concrete,the loaded raw material include at least coarse recycled aggregate. Amix proportion of raw materials is programmed in a controlling plantcomputer that weighs the raw materials necessary for the programmed mixproportion, the measured raw materials including a weight of coarseaggregate such that the weight of coarse aggregate comprises at leastabout 70% or more coarse recycled aggregate and the remaining weightcomprises coarse virgin aggregate and a weight of cement and fly ash.Once weighed and measured, the raw materials are transferred to a batchmixer and mixed.

The technology of the present invention also provides mix proportionsfor ready-mix concrete such that at least 70% of the coarse aggregatecomprises recycled aggregate. The mix comprising about 564 pounds ofcement, about 141 pounds of fly ash, about 35.3 ounces of water reducingagent (“WRA”), about 1260 pounds of recycled 57 rock, about 420 poundsof virgin 57/67 rock, about 1260 pounds of sand, about 220 pounds ofwater, and air-entraining admixture (“AEA”) wherein a ready-mix concreteis made having about 70% coarse recycled aggregate.

The technology of the present invention also provides mix proportionsfor ready-mix concrete such that at least 70% of the coarse aggregatecomprises recycled aggregate. The mix comprising about 526 pounds ofcement, about 132 pounds of fly ash, about 32.9 ounces of water reducingagent (“WRA”), about 1275 pounds of recycled 57 rock, about 425 poundsof virgin 57/67 rock, about 1275 pounds of sand, about 218 pounds ofwater, and air-entraining admixture (“AEA”) wherein a ready-mix concreteis made having about 70% coarse recycled aggregate.

The technology of the present invention also provides mix proportionsfor ready-mix concrete such that at least 70% of the coarse aggregatecomprises recycled aggregate. The mix comprising about 489 pounds ofcement, about 122 pounds of fly ash, about 30.6 ounces of water reducingagent (“WRA”), about 1290 pounds of recycled 57 rock, about 430 poundsof virgin 57/67 rock, about 1290 pounds of sand, about 216 pounds ofwater, and air-entraining admixture (“AEA”) wherein a ready-mix concreteis made having about 70% coarse recycled aggregate.

The technology of the present invention also provides mix proportionsfor ready-mix concrete such that at least 70% of the coarse aggregatecomprises recycled aggregate. The mix comprising about 451 pounds ofcement, about 113 pounds of fly ash, about 28.2 ounces of water reducingagent (“WRA”), about 1295 pounds of recycled 57 rock, about 435 poundsof virgin 57/67 rock, about 1300 pounds of sand, about 205 pounds ofwater, and air-entraining admixture (“AEA”) wherein a ready-mix concreteis made having about 70% coarse recycled aggregate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrative of one embodiment relating topreparing ready-mix concrete using the technology of the presentapplication;

DETAILED DESCRIPTION

The technology of the present application will now be explained. Thetechnology will be explained with reference to particular composition,material, strength, and other requirements. As mentioned above, thereference is typically associated with an ASTM standard for a particulartype of concrete. While a specific material may be called out, such as,for example, cement, mountain, type I/II L.A., at a particular poundage,such as, for example, 564 lbs, one of skill in the art would recognizethat the particular composition called for is within a particulartolerance as defined by the ASTM standard. Thus, the present applicationmay state the material as about 564 lbs of cement, mountain, type I/IIL.A. wherein the term about, approximately, or similar term should beunderstood to mean within the tolerance as allowed by the existing ASTMstandard as they currently exist and change from time to time. Moreover,the technology of the present invention will be explained withparticular reference to exemplary embodiments and admixtures. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments. Moreover, embodiments described herein should be construedas exemplary unless explicitly stated otherwise.

ASTM standard means any ASTM standard relating to concrete includingASTM C 94 relating to ready-mix concrete and ASTM C685 relating toconcrete made by volumetric batching and continuous mixing to name buttwo of the numerous ASTM standards relevant to ready-mix concrete.

Generally speaking, concrete comprising, among other things, recycledmaterial has been frowned upon in the industry because of manydetrimental effects. Typically, using recycled material reduces, forexample, the strength of the concrete. Additionally, the ready-mixconcrete manufacturers have shunned using recycled material because ofthe abundance of virgin materials available to most ready-mixfacilities.

Particularly shunned in the past was the recycling of aggregatematerial, i.e., sand and rock. It has been found, however, that inproper combinations recycling aggregate materials provides unexpectedbenefits to the ready-mix concrete. For example, using recycled sand notonly reduces the need for virgin materials, which provides anenvironmental benefit, but also provides recycled cement that can beused for the gravel or rock portion of the aggregate. The recycledcement results from the crushing and screening operations to extract therecyclable sand.

Recycling concrete into the gravel or stone for ready-mix concrete alsoprovides unexpected benefit to the ready-mix concrete. Generally,recycled concrete that has been crushed, screened and filtered to theappropriate size generally provides a lighter mixture per volume thannon-recycled gravel or stone. Also, crushed concrete typically is afractured face material that typically increases the strength ofconcrete using a similar recipe. Reducing the weight and increasing thestrength allows for the carrying of a larger payload and allows lessmaterial for a similar cubic volume, which reduces overall resources.

While both recycled sand and recycled gravel or stone provide increasedbenefits, it has been found that particular combinations of materialswork well. In one particular embodiment, it has been found combiningabout 30% recycled gravel or stone with 70% virgin stone provides asatisfactory admixture. Some sample embodiments suing this combinationinclude the following ready-mix concretes:

Example 1 is a 30% coarse recycled aggregate ready-mix concretecomprising, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II Low 565 lbs 335 kg Alkali (“LA”) AEA, Eucon Air 40As needed As needed WRA, EUCON x15, 7 ozs/cwt 39.6 ozs 1531 mL CoarseAGG - Recycled (for 535 lbs 317 kg example, No. 57 Rock obtained fromcrushed and screened concrete rubble) Coarse AGG - Virgin (for example1230 lbs 730 kg Del Camino No 57/67 Rock) Fine AGG, Sand (anycombination of 1335 lbs 792 kgs virgin or recycled) Water 245 lbs (or145 kg (or 145 L) 29.4 gals)

The above and below combinations (for both 30% coarse recycled aggregateand 70% coarse recycled aggregate) are based on pre-mix weights (whichare allowed to be within a tolerance, such tolerance will be designatedas about or approximately), in other words, the mix proportions arelargely saturated, surface dry condition based weights and amounts. Themixtures for ready mix concrete identified above refer to specific typesof rock designated generally as 57 Rock and 57/67 Rock which would beunderstood in the art to refer to specifications associated withparticular standards, such as, for example, the Colorado Department ofTransportation specifications. The air-entraining admixture (“AEA”),such as, for example, Eucon Air 40 commonly used in concrete to ensuredurability in freeze-thaw conditions and is available from, for example,Euclid Chemical and as commonly understood in the art for both the 30%and 70% coarse recycled aggregate described above and below would besupplied consistent with conventional techniques for adding air to themix and as it is well within the ordinary skill of the art for someonemaking ready-mix concrete, it will not be explained herein. The waterreducing agent (“WRA”), such as, for example, Eucon x15 which is furtherdefined by the appropriate ASTMs as a Type A & F mid-range water reducerand is available from, for example, Euclid Chemical and as commonlyunderstood in the art for both the 30% and 70% coarse recycled aggregatedescribed above and below would be supplied consistent with conventionaltechniques for adding air to the mix and as it is well within theordinary skill of the art for someone making ready-mix concrete, it willnot be explained herein.

Using the above ready-mix concrete, the final product will generallyprovide satisfactory results for ASTM testing standards. For example,one batch provided a unit weight of concrete under ASTM C 138 as 143.4pcf. A yield under ASTM C 138 of 27.27 ft cubed. A slump under ASTM C143 of 3¼ inches. An air content under ASTM C 231 of 5.4% and awater/cementitious ration of 0.43 at 74° F.

A second embodiment of 30% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 452 lbs 268 kg FLY ASH, Nebraska, Class C 113 lbs67 kg AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7 ozs/cwt39.6 ozs 1531 mL Coarse AGG - Recycled (for 516 lbs 306 kg example, No.57 Rock obtained from crushed and screened concrete rubble) Coarse AGG -Virgin (for example 1204 lbs 714 kg Del Camino No 57/67 Rock) Fine AGG,Sand (any combination of 1285 lbs 762 kgs virgin or recycled) Water 250lbs (or 148 kg (or 148 L) 30 gals)

A third embodiment of 30% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 414 lbs 246 kg FLY ASH, Nebraska, class C 103 lbs61 kgs AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7 ozs/cwt35.7 ozs 1380 mL Coarse AGG - Recycled (for 500 lbs 297 kg example, No.57 Rock obtained from crushed and screened concrete rubble) Coarse AGG -Virgin (for example 1100 lbs 653 kg Del Camino No 57/67 Rock) Fine AGG,Sand (any combination of 1370 lbs 813 kgs virgin or recycled) Water 250lbs (or 148 kg (or 148 L) 30 gals)

A fourth embodiment of 30% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 517 lbs 307 kg AEA, Eucon Air 40 As needed Asneeded WRA, EUCON x15, 7 ozs/cwt 35.7 ozs 1380 mL Coarse AGG - Recycled(for 500 lbs 297 kg example, No. 57 Rock obtained from crushed andscreened concrete rubble) Coarse AGG - Virgin (for example 1130 lbs 670kg Del Camino No 57/67 Rock) Fine AGG, Sand (any combination of 1290 lbs765 kgs virgin or recycled) Water 242 lbs (or 144 kg (or 144 L) 29.1gals)

A fifth embodiment of 30% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 564 lbs 335 kgs FLY ASH, Nebraska, Class C 141lbs 84 kgs AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7ozs/cwt 35.3 ozs 1365 mL Coarse AGG - Recycled (for 475 lbs 282 kgexample, No. 57 Rock obtained from crushed and screened concrete rubble)Coarse AGG - Virgin (for example 1105 lbs 656 kg Del Camino No 57/67Rock) Fine AGG, Sand (any combination of 1200 lbs 712 kgs virgin orrecycled) Water 250 lbs (or 148 kg (or 148 L) 30 gals)

A sixth embodiment of 30% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 705 lbs 418 kg AEA, Eucon Air 40 As needed Asneeded WRA, EUCON x15, 7 ozs/cwt 35.3 ozs 1365 mL Coarse AGG - Recycled(for 475 lbs 282 kg example, No. 57 Rock obtained from crushed andscreened concrete rubble) Coarse AGG - Virgin (for example 1105 lbs 656kg Del Camino No 57/67 Rock) Fine AGG, Sand (any combination of 1200 lbs712 kgs virgin or recycled) Water 250 lbs (or 148 kg (or 148 L) 30 gals)

While the above six embodiments are provided, one of ordinary skill inthe art will recognize and understand other combinations resulting inother mix proportions are possible.

Another combination that has been discovered to work particularly wellincludes a combination of about 70% recycled gravel or stone with 30%virgin stone. Some particular admixtures include the following ready-mixconcretes.

A first embodiment of a 70% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 564 lbs 335 kgs FLY ASH, Nebraska, Class C 141lbs 84 kgs AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7ozs/cwt 35.3 ozs 1365 mL Coarse AGG - Recycled (for 1260 lbs 748 kgsexample, No. 57 Rock obtained from crushed and screened concrete rubble)Coarse AGG - Virgin (for example 420 lbs 249 kgs Del Camino No 57/67Rock) Fine AGG, Sand (any combination of 1260 lbs 748 kg virgin orrecycled) Water 220 lbs (26.4 131 kgs (131 L) gals)

A second embodiment of a 70% coarse recycled aggregate ready-mixconcrete includes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 526 lbs 312 kgs FLY ASH, Nebraska, Class C 132lbs 78 kg AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7ozs/cwt 32.9 ozs 1272 mL Coarse AGG - Recycled (for 1275 lbs 756 kgsexample, No. 57 Rock obtained from crushed and screened concrete rubble)Coarse AGG - Virgin (for example 425 lbs 252 kgs Del Camino No 57/67Rock) Fine AGG, Sand (any combination of 1275 lbs 756 kgs virgin orrecycled) Water 218 lbs (26.2 129 kgs (129 L) gals)

A third embodiment of a 70% coarse recycled aggregate ready-mix concreteincludes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 489 lbs 290 kgs FLY ASH, Nebraska, Class C 122lbs 72 kgs AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7ozs/cwt 30.6 ozs 1183 mL Coarse AGG - Recycled (for 1290 lbs 765 kgsexample, No. 57 Rock obtained from crushed and screened concrete rubble)Coarse AGG - Virgin (for example 430 lbs 255 kgs Del Camino No 57/67Rock) Fine AGG, Sand (any combination of 1290 lbs 765 kgs virgin orrecycled) Water 216 lbs (25.9 128 kg (128 L) gals)

A fourth embodiment of a 70% coarse recycled aggregate ready-mixconcrete includes, in combination:

Per 1.01 Per 1.01 Mix Proportions Cubic Yard Cubic Meter CEMENT,Mountain, Type I/II LA 451 lbs 268 kgs FLY ASH, Nebraska, Class C 113lbs 67 kgs AEA, Eucon Air 40 As needed As needed WRA, EUCON x15, 7ozs/cwt 28.2 ozs 1090 mL Coarse AGG - Recycled (for 1295 lbs 768 kgsexample, No. 57 Rock obtained from crushed and screened concrete rubble)Coarse AGG - Virgin (for example 435 lbs 258 kgs Del Camino No 57/67Rock) Fine AGG, Sand (any combination of 1300 lbs 771 kgs virgin orrecycled) Water 205 lbs (24.6 122 kgs (122 L) gals)

While the above ready-mix concretes were made using 100% virgin sands,it is believed any amount of recycled sand from 0% to 20% could be usedin place of or in combination with virgin sand.

Referring now to FIG. 1, a flowchart 100 is provided illustrating onepossible methodology for making a ready-mix concrete using recycledmaterials. First, at step 102, the raw materials for the particularconcrete composition are provided to a manufacturing plant. The rawmaterials may include, in no particular order:

Virgin Sand;

Virgin 57/67 Rock;

Virgin Pea Gravel;

Recycled 56/67 Rock;

Recycled Washed Sand;

Cement Type I/II (preferably low alkali);

Fly Ash Type C;

Admixtures as a matter of design choice and end use; and

Water (preferably fresh and potable).

Next, the raw materials are loaded into storage bins, step 104. A mixproportion is set in a controlling plant computer, step 106. Whiledescribed in relation to preparing a single mix of ready-mix concrete,one of ordinary skill in the art will recognize on reading thedisclosure that a plant typically batch loads mix proportions into thecontrolling plant computer to run numerous mixes automatically.Optionally, once the mix proportions are set, the controlling plantcomputer may check the appropriate raw materials are loaded in the bins,step 108. A delivery vehicle, typically a truck, is located at the plantoutlet to receive the ready-mix concrete once the batch is prepared,step 110. Next, the controlling plant computer operates bin valves orgates to cause each bin to unload material onto an associated scaleuntil an appropriate amount of material is measured, step 112. Oncemeasured, the raw material is transferred to the truck, step 114. Thetruck mixes the raw material, typically 120 revolutions of the truckholder, step 116. Optionally, after the revolutions, the batch ofready-mix concrete is checked for quality, step 118, and delivered tothe appropriate site, step 118.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

1. A method of making ready-mix concrete using with at least 70% coarserecycled aggregate, the method comprising the steps of: loading rawmaterial bins with material in mix proportions for a ready-mix concrete,the loaded raw material including at least coarse recycled aggregate;programming a mix proportion of raw materials in a controlling plantcomputer; weighing the raw materials necessary for the programmed mixproportion, the measured raw materials including a weight of coarseaggregate such that the weight of coarse aggregate comprises at leastabout 70% or more coarse recycled aggregate and the remaining weightcomprises coarse virgin aggregate and fly ash; transferring the rawmaterials to a batch mixer; and mixing the raw materials into ready-mixconcrete.
 2. The method of claim 1, further comprising the step ofproviding the raw materials to be loaded into raw material bins.
 3. Themethod of claim 1, further comprising the step of checking that the rawmaterial bins contain the raw materials associated with the programmedmix proportion of raw materials.
 4. The method of claim 1, wherein thebatch mixer comprises a truck.
 5. The method of claim 4, wherein thestep of mixing the raw materials comprises causing a bin on the truck torevolve.
 6. The method of claim 5, wherein the step of mixing includesat least 120 revolutions of the bin on the truck.
 7. The method of claim6, further comprising the step of quality checking the batch ofready-mix concrete.
 8. A ready-mix concrete made from a combination ofmaterials comprising: about 564 pounds of cement; about 141 pounds offly ash; about 35.3 ounces of water reducing agent (“WRA”), about 1260pounds of recycled rock; about 420 pounds of virgin rock; about 1260pounds of sand; about 220 pounds of water; and air-entraining admixture(“AEA”) wherein a ready-mix concrete is made having at least about 70%coarse recycled aggregate.
 9. The ready-mix concrete of claim 8, whereinthe cement is type I/II low alkali and the fly ash is class C.
 10. Theready-mix concrete of claim 9, wherein the virgin rock is rock and therecycled rock is 57 rock.
 11. A ready-mix concrete made from acombination of materials comprising: about 526 pounds of cement; about132 pounds of fly ash; about 32.9 ounces of water reducing agent(“WRA”), about 1275 pounds of recycled rock; about 425 pounds of virginrock; about 1275 pounds of sand; about 218 pounds of water; andair-entraining admixture (“AEA”) wherein a ready-mix concrete is madehaving at least about 70% coarse recycled aggregate.
 12. The ready-mixconcrete of claim 11, wherein the cement is type I/II low alkali and thefly ash is class C.
 13. The ready-mix concrete of claim 12, wherein thevirgin rock is 57/67 rock and the recycled rock is 57 rock.
 14. Aready-mix concrete made from a combination of materials comprising:about 489 pounds of cement; about 122 pounds of fly ash; about 30.6ounces of water reducing agent (“WRA”), about 1290 pounds of recycledrock; about 430 pounds of virgin rock; about 1290 pounds of sand; about216 pounds of water; and air-entraining admixture (“AEA”) wherein aready-mix concrete is made having at least about 70% coarse recycledaggregate.
 15. The ready-mix concrete of claim 14, wherein the cement istype I/II low alkali and the fly ash is class C.
 16. The ready-mixconcrete of claim 15, wherein the virgin rock is 57/67 rock and therecycled rock is 57 rock.
 17. A ready-mix concrete made from acombination of materials comprising: about 451 pounds of cement; about113 pounds of fly ash; about 28.2 ounces of water reducing agent(“WRA”), about 1295 pounds of recycled rock; about 435 pounds of virginrock; about 1300 pounds of sand; about 205 pounds of water; andair-entraining admixture (“AEA”) wherein a ready-mix concrete is madehaving at least about 70% coarse recycled aggregate.
 18. The ready-mixconcrete of claim 17, wherein the cement is type I/II low alkali and thefly ash is class C.
 19. The ready-mix concrete of claim 18, wherein thevirgin rock is 57/67 rock and the recycled rock is 57 rock.